The present invention relates to a weaving-machine auxiliary nozzle which is configured as a hollow needle which, in a wall adjoining a closed tip, includes one or several outflow apertures that, when the auxiliary nozzle is mounted on the weaving machine, is directed towards a filling-yarn insertion duct.
Such auxiliary nozzles are known from U.S. Pat. No. 5,020,574. They enhance filling insertion into a weaving machine""s shed. Several such auxiliary nozzles are distributed for that purpose across the width of the batten and they each supply a flow of fluid supporting the motion of a filling yarn blown into a filling yarn insertion duct associated with the batten. The auxiliary nozzles are arrayed in such a way that blow aperture(s) disposed in a wall underneath the tip shall point in a given direction toward the upper wall and the back wall of the filling insertion duct. The fluid streams from the blow apertures flow substantially in the longitudinal direction of the filling insertion duct and include an upward and oblique component.
During weaving the auxiliary nozzles move through the lower plane of warps into the shed at each filling insertion. It was observed that warps consisting of several thin and individual filaments and exhibiting only a slight twist will fray/unravel at those sites where the auxiliary nozzles pass through the plane of the warps in one direction into and then back out of the shed. Such fraying/unraveling arises foremost in filament yarns wherein thin synthetic filaments substantially run parallel to one another and are welded to each other at regular spacings. In such cases the fabric has an appearance at the sites where the auxiliary nozzles move through the lower warp plane that differs from the appearance of the remaining fabric. These warps are bulkier in the region of the auxiliary nozzles than the remaining warps because these thin filaments no longer are rigorously configured next to each other.
It is the objective of the present invention to design an auxiliary nozzle of the above described kind so that the danger of damaging the warps is reduced.
This goal is attained in that in its tip area the hollow needle includes a bulge pointing towards the reed when the auxiliary nozzle is mounted on the weaving machine.
The auxiliary nozzle of the invention not only reduces the danger of finding its way between the individual filaments of a warp, but also precludes the fluid flow(s) through the outflow aperture(s) from adversely affecting the warps.
To facilitate moving the auxiliary nozzle through the lower plane of warps into and out of the shed, the invention appropriately assures that the bulge""s walls shall continuously adjoin the hollow needle""s walls. As a further advantage, the bulge includes a wall which is substantially flush with the wall that contains the outflow aperture(s).
In a further embodiment of the invention, the hollow needle""s inner volume expands into the bulge zone. In this case the cross-section of the inner volume may be decreased in the related perpendicular direction. As a result a further advantageous design allows increasing the thickness of at least the wall comprising the outflow apertures. This wall thickness may be increased without thereby decreasing the flow cross-section towards the outflow apertures and increasing the flow impedance, because the expansion of the inner volume increasing the flow cross-section in the bulge zone.
Thereupon, in a further embodiment of the invention, the outflow aperture(s) are designed as nozzles. Such nozzle allows improved collimation and directionality of the fluid jet(s), and as a result such jets will be more effective in driving a filling.
Moreover the bulge makes it also possible to place the cross-sectional surface of the outflow aperture(s) required for the given quantity of fluid closer to the tip of the hollow needle. This feature offers the advantage that the outflow aperture(s) when entering a shed will move earlier past the warps and when leaving the shed will move past them later, and consequently the time interval within which a fluid flow is supplied by the auxiliary nozzles can be enlarged without thereby affecting the warps.
In a further embodiment of the invention, the hollow needle""s tip comprises a substantially straight top edge extending as far as the bulge zone. Advantageously the top edge subtends an angle of 70 to 110xc2x0 with the hollow needle""s longitudinal axis.